Currently the NPN bipolar transistor in BiCMOS process usually uses heavily doped collector buried layer to reduce the collector resistance. This process also need n-type high dose and high energy implanting (above 1e15 cm−2) to realize collector buried layer connection and to form collector pick-up. The epitaxy layer on the collector buried layer forms the middle or low doped collector. The p-type doped silicon epitaxy forms the base and the heavy doped N-type poly silicon forms the emitter, then the fabrication of the bipolar is finished.